| IS | Athenian rhetorician and orator (436-338 BC) |
|---|---|
| IS | a salt or ester of isocyanic acid |
| IS | an acid known only in the form of its esters |
| IS | containing a closed ring of atoms of the same kind especially carbon atoms |
| IS | quillworts |
| IS | aquatic or marsh-growing fern allies |
| IS | type and genus of the Isoetaceae and sole extant genus of the order Isoetales |
| IS | a widely used inhalation anesthetic |
| IS | either of a pair of conjugating gametes of the same size and structure |
| IS | (biology) reproduction by the union or fusion of games of the same size and structure |
| IS | an imaginary line connecting points on the Earth's surface where the magnetic declination is the same |
| IS | an imaginary line connecting points on the Earth's surface where the magnetic declination is the same |